1. Field of the Invention
The invention relates generally to accessories for expanding the uses and applications of hand-held electric drills. More specifically, the invention pertains to an accessory saw for connection to the chuck of an electric drill, which utilizes the rotary power of the drill to drive a reciprocating saw blade at right-angles to the axis of the drill.
2. Description of the Prior Art
The prior art teaches a variety of accessory saw constructions, adapted for coupling to the rotary output of an electric hand drill. For example, in U.S. Pat. No. 5,755,293, granted to Bourke, a drill/saw apparatus is disclosed. In the Bourke device, bevel gears driven by an electric drill rotate an eccentric peg, held captive in a slot in a blade drive arm. The reciprocating action of the blade drive arm actuates the saw blade accordingly. The hexagonal drive shaft which transfers power from the electric drill to the apparatus maybe inserted into the apparatus housing at a plurality of positions. A similar arrangement is shown in U.S. Pat. No. 5,566,768, also granted to Bourke, for a drill attachment using helical and worm gears.
U.S. Pat. No. 3,398,588, issued to Meier, shows a reciprocating hand tool attachment for hand drills. Meier""s device employs a pair of pulleys, connected by a friction drive belt. One of the pulleys has an eccentric cam for providing the reciprocating drive for the saw blade support mechanism.
In Lee, et al., U.S. Pat. No. 2,822,005, a jig saw attachment is disclosed which attaches both to the rotary output shaft and to the body of an electric drill. A motion converting mechanism includes a crank shaft head and an eccentrically mounted crank pin. Right angle reciprocating drive for the jig saw blade is thereby provided.
A reciprocating attachment for hand drills is shown in U.S. Pat. No. 5,607,265, issued to Lane. The attachment comprises a housing containing a grooved shaft. The saw blade is attached to a holder, which in turn, is operably connected to a bearing within the groove. A drill retainer clamps both to the drill and to the housing, preventing the housing from rotating.
Dedicated electrically powered reciprocating saws also exist, such as the SAWZALL brand saw, manufactured by the Milwaukee Tool Company. Although exhibiting high performance for their intended use, such dedicated reciprocating saws act in a direction which is coincident with or parallel to the axis of the tool. This limits the saw""s usefulness when use is attempted in confined areas. In addition, dedicated reciprocating saws are expensive, and relatively large and heavy to use.
However, in many applications, sawing must occur in tight quarters, such as in attics or in crawl spaces beneath a house. In these circumstances, the need exists for a compact, right-angle reciprocating saw, which can saw at an angle which is 90 degrees from the axis of the tool which the user is grasping.
The need further exists for an accessory saw, for use with an existing electric hand drill, which is inexpensive, light in weight, and quick to connect and disconnect from the electric drill.
The need also exists for a right-angle accessory saw which can be manually rotated about the axis of the main drive shaft of the electric drill into a plurality of selected cutting positions, while the electric drill remains in a fixed position, in the hands of the user.
The need further exists for a right-angle accessory saw having a saw head which can be manually rotated about its axis into a plurality of selected cutting positions, while the electric drill remains in a fixed position, in the hands of the user.
The right-angle accessory saw of the present invention includes a drive shaft housing having a proximate end and a distal end. An elongated drive shaft is mounted for rotation within the drive shaft housing. The drive shaft has a drill connection end, extending outside and past the proximate end, for insertion into the chuck of a electric hand drill. The other end of the drive shaft terminates in a cam end, with a rotary cam mounted thereon. The cam is located within the distal end of the drive shaft housing.
The accessory saw also includes a saw head, having an inner end and an outer end.
The inner end of the saw head is rotatably mounted to a port in the side of the distal end of the shaft housing. The axis of the saw head is transversely position with respect to the axis of the shaft housing, extending at a right angle therefrom.
A push rod is mounted for reciprocating translation within the saw head. The push rod includes a cam follower on an interior end, and a saw blade holder on an exterior end. The cam follower extends into the distal end of the drive shaft housing, where it maintains contact with a cam surface of the cam. The push rod is spring-biased inwardly toward the cam, thereby maintaining the cam follower in substantially continuous contact with the cam surface at all times.
A saw blade of choice is installed in the saw blade holder. A simple screw and compression plate mechanism is disclosed which allows the user to install, remove, and change saw blades for the particular application at hand.